The BBC's Peter Stevens: 'Iran...has been engaged in more of a charm offensive'

The White House said the Iranian missile, known as a Shehab 3, is based on a North Korean weapon, which has a range of around 800 miles (1,300km).

President Clinton said he was 'concerned, but not surprised' by the news of the test, which he added could threaten the already fragile stability of the Middle East.

A senior US official told The New York Times that the missile was capable of altering the political and military balance of power in the region.

"This weapon would allow Iran to strike all of Israel, all of Saudi Arabia, most of Turkey and a tip of Russia," the official said.

Yizhak Mordechai appeals to "freedom countries"

Israel's defence minister, Yitzhak Mordechai, described the test as very worrying. He said it posed a grave threat to the Middle East, and Israel in particular.

The BBC Washington correspondent says the main concern in the US is that Iran might want eventually to develop a nuclear warhead, and extend its military influence in the region.

He says that Israel's response is also important. Although there is a large time-lag between missile tests and the deployment of any threatening weapons, he says Israel would not be expected to sit back and do nothing if a threat emerged.

US State Department's James Rubin: "Iran will have the ability to strike more distant targets"

The test was detected by American satellites on Wednesday. It was confirmed by White House spokesman Mike McCurry following reports by officials in the Washington Post and the New York Times.

Mr McCurry said the test was a source of concern to the US. He added that Iranian acquisition of North Korean technology was fully consistent with what the US had been worried about for some time.

The launch comes a month after the US and Iran agreed to work at improving relations in the wake of the victory of the moderate President, Mohammed Khatami, in last year's elections.

Iran, which has a well established Scud missile programme dating to the 1980s, is reported to be working on developing a nuclear warhead, but is believed to be years away from building a weapon.

BBC Washington Correspondent Stephen Sackur: Confirmation of long-term worries

"This test shows Iran is bent on acquiring nuclear weapons, because no one builds an 800-mile missile to deliver conventional explosives," Gary Milhollin, an expert on the spread of weaponry, told the New York Times.

However, the BBC Middle East correspondent says the idea of Iran suddenly attacking pro-Western Arab states is at the moment improbable.